Multiplex telegraphy



Sept. 7 1926.

, 1,599,344 F. E. PERNOT ET AL MULTIPLEX TELEGHAPBY ori inal Filed March 10. 1923 s She'ets-Sheet 2 v/srmrmc, REED 34 GENE/i'ATO R 7 SPEED ALTERNATOR CONTROLLER Sept. 7 1926. 9 1,599,344

7 F. E. PERNOT ET AL MULTIPLEX TELEGRAPH! Original Filed March 10. 1923 s Sheets-Sheet 3 Patented Sept. 7, 1926.

"UNITED STATES insert PATENT o en FREDERICK EUGENE runner AND LESTER/JACOB RICH, or LONDON, ENGLAND."

MULTTPLEX TELEGRAPHY."

Application filed March 10, 1323, Serial No. 624,224, and. in Spain March 15, 1922. Renewed June '7, 1926.

This invention has reference to improvements in and applicable to multiplex, telegraphv and has particular, although not exclusive, reference to the vmeans for and the method of transmitting the receiving electric current signals over submarine cables. i

The principal object of the present invention is the provision of improved means for enabling duplex direct urrent and either simplex or multiplex alternating current to work simultaneously over one and the same cable. I

Further objects of this invention are the provision of means for increasing the selectivity of the circuits and foreliminating or minimizing interference between the several currents in the circuits and of improved means for effecting adjustment of the alternating current receiving apparatus.

The principal feature of this invention consists in the provision and arrangement in a system for. multiplex telegraphy employing superposed duplex direct current and either simplex or multiplex alternating current of a transient moderator comprising, for example networks of impedances which serve to eliminate or minimize disturbance of the local alternating current receiver or receivers by local transmit-ted direct current.

Another feature consists in so introducing and removing the local alternating current electromotive force or forcesthat the remote direct current receiver may be sensibly un aflected by currents produced thereby.

Further features of this invention Will be evident from examples of carrying the invention into effect hereinafter described.

Figure 1 of the accompanying diagranu matic drawings representsone method of carrying out this invention.

Figure 2 represents in detailon-e arrangement'according to the present invention for minimizing disturbance ofthe remote direct currentreceiver by locally transmitted alternating current.

The particular arrangement illustrated in accompanying Figure 1 is particularly adapted to duplex direct current and sim plex alternating current working either independently or simultaneously but it 1s to be understood that this particular arrangement may be adapted to duplex or multiplex alternating currentworki'ng without departing from the principal feature of the inventern.

tion; such ada-ptation consistingonly in the incorporatlon into the system of. a multiplicity of parts pertaining to the alternatlng current system and the "inclusion of selective means in the alternating current circuits.

Referring to Figure l, the cable for transmitting the signals is represented at 1 and the artificial cable for balancing is represented'at 2, one arm v3 of the duplex bridge artificial line for currents of su-chfrequency as are used Close coupling 9 between the coils v5 and 6 provides for a low e'lfectiveimpedanee for outgoing currents entering at the apex and a high impedance for infiowing currents from cable to artificial line.

The two arms of the bridgeare joined at the apex by a resistance 10 and connection is taken therefrom to the direct current and the alternating current transmitting apparatus, the respective circuits therefor thus being in parallel between the bridge and earth. v 1 Y Referring to the direct current transmitting apparatus "18, this apparatus may be ,of 'any usual or convenient type but the in the alternating current sys current generated is caused to pass first through a transient moderatorbefore pass ing through the ordinary. apex inductance tothe'bridge apex.

The apex inductance represented at 11 conveniently conforms to usual practice and incidentally assists in preventing alternating current signals fromx being by-passed through the direct current transmitting apparatus. The transient moderator is a device which, owing to its characteristic of impeeling the passage of'alternating currents between certain ranges of, frequency, preventsor tends to prevent the local alternating current receiving apparatusfrom being improperly actuated by' locally" transmitted direct current as a result of imperfection in bridge balance. The transient moderator illustrated in Figure 1 comprises inductances 12 13 and 14 and condensers 15 16 and 17, connected substantially as shown.

One lead 18 from the direct current transmitting apparatus 18 makes connection With a closed circuit 19 having the induc tance 13 and condenser 16 in parallel. Circuit 19 makes connection with a closed circuit 20 having inductance 12 and condenser 15 in parallel and this latter circuit is directly connected to the apex inductance 11.

The other lead 21 from the direct current transmitting apparatus is earthed at 22 and a connection 23 is taken from this lead to the connection between the closed circuits 19 and 20, inductance 14 and condenser 17 being in series with connection 23. v

A further lead 24 is taken from earth to the double relay 25 of the alternating current transmitting system and a condenser 26 placed inseries therewith, such condenser serving to prevent direct current signals being by-passed through the alternating current system. The other lead 27 from the relay 25 makes connection at or near the bridge apex with lead 18.

In direct connection with the relay 25 is the alternating current transmitter 28 of any usual or convenient type.

The transmitter alternator 30, motor 31, alternator 32, speed controller 88 and vibrating reed generator 34 of the alternating current system may be of any convenient type and are connected as diagrammatically indicated. 7

The usual inductive recorder shunt 35 across the arms 3 and 4 is provided as shown and leads 36 and 37 from said arms respectively to the direct current receiving apparatus 36. r

In circuit with the direct current receiv ing apparatus, which apparatus is of any usual or approved type, it is preferred to employ a relay screen conveniently comprising inductive coils 38 and 39 wound round a laminated core 40 and there being provided a condenser 41, connections being made as shown.

The function of said relay screen is to prevent currents of similarfrequency to that used for the alternating current system currents which are liable to be generated by vibrations of the coils, armatures or other moving parts associated with the direct current receiving apparatus from flowing back into the duplex bridge and thereby disturb. ing the alternating current receiving apparatus.

For the purpose of allowing of alteration of the balance of the alternating current receiving System without materially disturbing the balance of the direct current system (which is a practically indispensable refinement when operating duplex) auxiliary balancing means are placed in circuit with thearms of the duplex bridge. The example of auxillary balancing means illustrated in Figure 1 is constituted by suitabl variable impedances 42 and 43 in circuit with the arms 3 and 4 respectively. One lead 44 to the alternating current receiving system is taken from that side of the impedance 42 remote from the bridge apex and the other lead 45 to the alternating current receiving system is taken from that side of the impedance 43 nearer to the bridge apex. Alternately, the leads 44 and 45' may be taken from the opposite sides of the respective impedances 42 and 43 as represented by the dottedline 46.

By reason of providing said auxiliary balancing means a refinement of the balance for the alternating current system may be obtained without disturbing that of the direct current system.

Leads 44 and 45 connect the amplifier 48, 49 for the alternating current receiving system to the duplex bridge; as shown, and in circuit with the lead 45'is a condenser 47 which is adapted to prevent the amplifiers 48 and 49 in circuit with the leads 44 and 45 from bypassing the incoming direct current signals to a harmful extent.

To further assist in removing the effect of the direct current incoming signals a mutual inductive coupling 47 is preferably inserted in the leads 44 and 45 intermediate the bridge arms 3 and 4 and the amplifier 48, each coil of such coupling being in parallel with. a condenser 48. Additionally a non-inductive resistance may be connected in the lead 45 as shown at 45'.

Connection is made from the amplifier 49 through a transformer 50 to polyphase relays 51, the function of the transformer being to ensure that the circuit leading up to the re lays siiall be characterized by an inductive impedance so as to stabilize the deflections of the relays. as well as to ensure that the current supplied. to the relays contains no uni-- directional component and also to provide an eflicient coupling between the relays and the output circuit of the amplifier; if they are of widely different impedances.

The polypliase relays illustrated in Figure 1 are of the known type incorporating two coils disposed in magnetic fields which are excited by out-of-phase currents provided by the alternator 82 and act as relays for the operation of any further desired devices such is suitable receiver The current supplied to the fields of the relays by the alternator 82 is as nearly as possible of the same frequency as that which constitutes the incoming alternating current signals.

The said polyphase alternator further excites a phase shifting transformer The adjustable phase output of this trans Ill;

also provided in said circuit.

. by means for the variable resistances 53 and 54, connected as shown, resistance 54 being in series with the cable 1 and resistance 53 being in circuit with leads taken from the cable 1 one on each side of resistance 5a to the transformer 52. A switch as at is The function of the above described phase shifting transformer is to provide a current of definite phase and frequency for use While adjusting the polyphase relays in a manner Well known to persons versed in thisart and the said current is not for'use either in the transmission or reception of messages. I l

It should be noted that the motor 31 drives all the other machines through gearing, as shown, and by reason of the speed of the mo tor being controlled (suitable mechanism, not forming subject-matter for this specification, being utilized therefor) the speed oi the. machine driven thereby is likewisecontrolled. I p

In general, the sudden introduction of an alternating E. -M. F. into a cable system will result in a current at some remote point having an integral value over a finite time interval different from-zero and greater than any possible integral over half cycle. Such an integral value is efl'ective'in' operating a directcurrentreceiving device and to avoid such action We provide a contact maker represented by 29 in Figure 1 in order to ensure that the outgoing alternating current are established and dis-established at definite predetermined points in the cycle so as to prevent them from'intertering \vith'the direct current receiving apparatus at the remote end of the cable. r

A preferred contact making and'breaking levlce according to the present lnvention is illustrated inFigure 2, in which the circuit a Z) is to be openedand closed subject to the conditions stated above by the key is. 0 is a slip ring geared to the alternator generat-- in'g current for the transmission of the requisite signals, such slip ring making one revolution per cycle. (Z and c are brushes, male inn contact with the slip ring. I

The slip ring and brushes are so constructed and so placed relative to one another that the brushes are electrically connected together at that instant. during the cycle When it is desired to start the current and are electricallydisconnected at that in stant during the cycle When it is desired to.

terminate the current. f and g are cams geared to the alternator and making one revolution per cycle. Cam 9 Works the electrical contacts m and n, the adjustment being such that contact mcloses just after brushes (Z and c are disconnected and opens just before the brushes are connected to-- gether and contact 1% closes just after the brushes are connected together and opens just before the br shes are disconnected. Cam f Works the electrical contacts 0 an l p,

the adjustment being such that contact 0 I opensbrieiiy While contact m is closed and contact 39 opens briefly While contact a 13 closed.

tacts r and 8 and tis anelectromagnet WO'lli' the electron'iagnets. The various parts" are electrically interconnected shown in the dis-grain. i

This arrangement performs its function in the following manner :-Vl hile the key l: remains open contacts 1", 8', u and o remain open; hence, circuit or 2') remains open. ii hen the key 7; isclosed nothinp; .ha nzensuntil' contact at also closes; this starts the current in electroinagnet. 15, closing contacts uand '21. Brushes ci and e are then connected to gether by the'rotation of the slip ri. 1., closingcircuit, a Z) at the proper instant.

in; the manner Contact a then clos'e'sythis starts the cur rent in the electromagnetg} closing contacts/1" and 8. Circuit (4 Z) is'noiv closed through contacts 7 and u and remains'closed as long. 'as the key k is held down; Wltren the he;

leis released nothing hap iiens until cont ct p opens;.this interrupts the current in elem tromagnet {7 releasing contacts a" and s. Brushes Z and c are then disconne'cted by the rotation of the slip ring opening circuit a b at the proper ins-taint. opens; this interrupts the current in electromagnet t, releasing contacts a and ap aratus h'as' noyv returned ,to its original condition;and is ready to go through the same series or operations Whenever the key his again depressed.

The desired action "cansecured by placing' the alternating" current signalling key in the field circuit or the sending alternator Without turn] er precautions. Theuse of the contact in field circuit, operating" at tie the cycle. provides a still more per trol of this source of inter leren s than doc'. the use otthe contact mal-rer in thealte tor output circuit only.

that the terns on a cable .operatine normally With.

g is an electroma 'uet Warning con cu rrent Contact 0 then The in some cases be direct current is restricted to currents \vithin a comparativel; cies. The rapid pulsations ..a;iau rect current signalling set a lower limitand. the rapid increase in attenuation. along; the

cable with higher frequencies sets the upgizer limit.

II" the alternating current Worked duplex, then the two mes; for-the above reason be conveyed b .czar

svsteni be rents of nearly equal frequency. To be specific, suppose that in the arrangement hereinbefore described the transmitting alternator produces -cycle current and the receiving alternator (SO-cycle current. That means that outgoing messages are at 50 cycles and incoming at cycles. I

If the duplex bridge balance were perfect, then the system would be oirectly available for duplex alternating current Working, for the outgoing 50-cycle current Would not interfere With the reception of 60-cycle current by the amplifiers and relays. It is doubtful if such a nearlyperfect balance can be obtained and fmaintained so that it becomes necessary to make the alternating current receiving system so selective as regards frequency that imperfections in balance do not interfere With reception at, say, the 60 cycles even though there exists considerable disturbance from the outgoing current of 50 cycles.

We claim 1. In a system of multiplex telegraphy duplex bridges, connection, therebettveen, direct current transmitting and receiving apparatus, alternating current transmitting and receiving apparatus, connection from the bridge to earth, transmitting apparatus connected to said bridge and a plurality of impedances for suppressing such currents resulting from the transmission of direct current as possess a frequency of the same order as that of the received alternating current.

2. In a system ofmultiplex telegraphy duplex bridges, connection therebetween, trans mitting apparatus connected to said bridge,

receiving apparatus connected across said bridge and means located int-ermedlate the.

bridge and direct current transmitting apparatus for suppressing such currents resulting from the transmission of direct current as possess a frequency of the same order as that of the received alternating currents.

3. In a system of multiplex telegraphy duplex bridges, transmission line and artificial line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, connection from the bridge apex to earth, closed circuits in series With one another in said connection, a condenser and inductance in parallel in each of said circuits, a connection adjacent one of said circuits to earth, a. condenser and inductance in series in said latter circuit, direct current transmitting apparatus in said apex-earth, connection, and alternating current transmitting apparatus in parallel with the direct current transmitting apparatus and associated circuits.

4. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, connection from one bridge apex to earth; a direct cur renttransmitting apparatus located in said connection, impedances also located in said connection for suppressing such currents resulting from the transmission of direct current as possess a frequency of the same order as that of the received alternating current, alternating current transmitting apparatus for transmitting signals over the said liner and means for so introducing the transmitted alternating currents into circuit and removing them therefrom that remote direct current receivers are substantially unaffected thereby.

5. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, connection from one bridge apex to earth, direct current transmitting apparatus located in said connec tion, alternating current .transmitting apparatus for transmitting signals over the said line, and means for introducing and'Withdrawing the alternating currentsignalling current at pre-determined phases of the cycle of alternation.

6. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, connection from one bridge apex to earth, direct current transmitting apparatus located in said connection, alternating current transmitting apparatus in parallel With said connection and earth, a'transient moderator located in said connection, and meansfor introducing and Withdrawing the alternating current signalling current, pre-determined phases of the cycle of alternation.

Hit)

7. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current and alternating current receiving apparatus, and a transient moderator, sources of direct and alternating signaling currents, said transient moderator being interposed between said source of direct signaling current and said transmission l1ne for preventing the alternating current receiving apparatus from being affected by interfering currents. J

8. In a system of multiplex telegraphy duplex bridges, a transmission line therebetween, a plurality of impedances for preventing locally produced direct current from improperly actuating local alternating current receiving apparatus and the armature of an electric current generator connected to said line, a transmitter in the field of said generator and operation of said-transmitter producing signals in, the line.

9. In a system of multiplex telegraphy duplex bridges, a transmission line, a tranllO ergyand said transient, moderator and the line whereby the eiiect of said other source upon said first mentioned source is substantially eliminated. w a 10. In a system of multiplex telegraphy duplex bridges atransmission line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, a transient moderator,

the alternating current generator and transmitter connectedto contacts, cams controlling the opening and closing of said cont acts, and means for imparting rotary motion to said camsfrom the alternator.

- 11. Ina system of multiplex telegraphy a duplex bridge, a transmission line, direct current receiving and transmitting apparatus, alternating current receiving and trans mitting apparatus, a transient moderator, an alternating current generator andtransmitter, tl egenerator armature connected to the transmission line, switches in said connection, elect-rom'agnets for opening and closing said switches, a local; source for sup-. plying current to said magnets, switches connected to the alternating current transmitter, said latter switches controlled by said magnets and connected to contacts,

said contacts controlled by cams, and means for imparting rotation to said cams from the alternator so that the alternating current is introduced and withdrawn from the transmission system only at predetermined phases of the cycle of alternations of said current. I

12. In a system of multiplex telegraphy, duplex bridges, a transmission line, direct current receiving and transmitting apparatus, alternating current receiving and transmitting apparatus, a transient moderator, auxiliary balancing means variable impedances located in the bridge arm, said alternating current receiving apparatus being connected adjacent said auxiliary balancing means whereby said means render the received alternating current receiving apparatus immune from the effects of locally transmitted currents.

13. In a system of multiplex telegrapliy a duplex bridge, a transmission and an artificial line, transmitting and receiving ap paratus, a transient moderator, variable 1mpedances in two of the bridge arms, leads from each of said arms to the alternating current receiving apparatus, one ofsaid leads located on that side of the impedance in one arm remote from the bridge apex and the otherlead located on that side of the other impedance in the other armnearer the bridge-apex. 1

14:- In a system of multiplex telegraphy a duplex bridge, a transmission and an artificial line, transmitting and receiving apparatus, a transient moderator comprising a pairof series branches each containing an inductance shunted, by a capacity-and an intermediate branch containing; inductance and capacity connected in seriesanddis posed in parallel with. respect to thetransmission line, leadsiromj the alternating current receiving apparatus to the bridge arms, amplifiers in said leads and an inductive coupling intermediatevsaid amplifiers and arms said transient moderator being int-erposed between the transmission line and a portion of the transmittingapparatus- 15. In asystem of multiplex telegraphy a duplexbridge, a transmission and an artiiicial line, transmittingand receiving apparatus, a transient moderator comprising impedance in series and in parallel said moderator interposed between the transmission line and a portion of thetransmitting apparatus connection from the alternating current receiving-apparatus to the bridge, said connection including an inductive coupling and means for amplifying the alternating current signals.

16. In a system of multiplextelegraphy a duplex bridge, a transmission and an artificial line, transmitting and receiving apparatus, a transient moderatorcomprising impedance in'series and in parallel. and a dif ferential choke in each bridge arm.

17. Ina system, of multiplex telegraphy a duplex bridge, a transmission and an artificial line, transmitting and receiving apparatus, a transient moderator comprising a plurality of condensers and inductances connected between the transmission line and the transmittingapparatus, and a dilierential choke in each bridge arm.

18. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current transmitting and receiving apparatus, alternating current transmitting and re ceiving apparatus, a transient moderator comprising impedance in series and in par 'allel, inductances in each bridge arm, said inductances being inductively coupled mutually and variably and located in said arms on that side of the direct current and alternating current receiving apparatus adjacent the bridge apex.

19. In a system of. multiplex telegraphy a duplex bridge, a transmission and an artificial line, transmitting and receiving apparatus, a transient moderator, leads from the bridge arms to the direct current receiving apparatus and a relay screen located in said leads.

20. In a system of multiplex telegraphy a duplex bridge, a transmission and an art-ificial line, transmitting and receiving apparatus, a transient moderator, leads from the bridge arms to the direct current receiving apparatus,'tWo coilsin series in one of said leads, said coils mutually inductively coupled, a connection from apoint intermediate said coils to the other lead and a condenser in said connection.

21. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current transmitting and receiving apparatus, alternating current transmitting and receiving apparatus, and a transient moderator, connected betWeen'said transmission line and said direct current transmitting ap-i paratus and arranged to prevent the alternating current receiving apparatus from being actuated by locally transmitted direct current energy.

22. In a system of multiplex telegraphy duplex bridges, a transmission line, direct current transmitting and receiving apparatus, alternating current transmitting and re ceiving apparatus, a transient moderator, said latter receiving'apparatus comprising tWorelays for each alternating current signalling channel, an alternating current supply to each field and the current supplied to one field being substantially in time phase quadrature With the current supplied to the other field.

23. In a system of multiplex telegraphy transient moderator, polyphase relays in the alternating current receiving system, independent fields to, each relay, an alternating current supply to each field, the current supplied to one field in time phase quadrature With the current supplied, to the other field, a phase shifting trans-former in parallel With each of said fields, connectionitroni said transformer to the bridge arms, said connection adjacent the transmission line, a key and variable resistances in said connection and said transformer providing a current of definite phase and frequency for use While adjusting the relays.

24. In a system of multiplex telegraphy duplex bridges, a transmission line direct current receiving and transmitting appara tus, alternating current receiving and transmitting apparatus, a transient moderator,

an apex inductance, a differential choke,

said choke located in the bridge arms, a relay screen, said screen located in the direct current receiving system, auxiliary balancing means and polyphase relays located in the alternating receiving system, means for introducing and Withdrawing the alternat ing current signals at definite phases of the alternation of said current, a condenser in each bridge arm, a resistance in parallel With each condenser and an inductance shunted across said arms. FREDERICK EUGENE PERNOT.

LESTER JACOB RICH.

Certificate of Correction. It is hereby certified that in Letters Patent No. 1,599,344, ranted September 7 1926, upon the application of Frederick Eugene Pernot and fiester Jacob Rich, of

London, England, for an improvement in Multiplex Telegraphy, errors appear in the printed specification requiring correction as follows: Page 4, line 58, claim 3, after the compound Word apex-earth strike out the comma; same page, line 74, claim 4, for the Word current, first occurrence, read currents; line 106, claim 6, before the Word predetermined insert the Word at; page 6, line 66, claim 24, after the Word alternating insert the Word current; and that the said Letters Patent should be read With these correctionstherein that the same may conform to the record of the case in the Patent Ofiice. I v

Signed and sealed this 5th day of October, A. D. 1926.

[SEAL] v M. J. MOORE,

Acting Commissioner of Patents. 

